In the past, attempts to improve the grip of a shoe have involved changing the materials or structure of the soles.
For example, US patent application 2013/036,633 discloses a non-slip sole structure of anti-slip shoes used for stream trekking and fishing is made of a material with a large coefficient of friction such as unwoven fabric and having regular or irregular hollow grooves formed at predetermined positions of the sole.
DE 101-31-354 describes a shoe sole having a non-slip structure with non-slip components, oriented on main alignments in zones which match the image of the human foot, to transmit the dynamics of natural walking movements into a maximum non-slip effect over the whole sole area. Some zones retain traction during the shifts of the body center of gravity, and the outer edge zone prevents slipping at the edge.